Creating ‘ghostly mirrors’ for high-power lasers DARPA Team Begins Work on Field Deployable Whole Blood Equivalent An illuminated water droplet creates an ‘optical atom’ Lightning Strikes Create a Strange Form of Crystal Rarely Seen in Nature MIT engineers grow “perfect” atom-thin materials on industrial silicon wafers New analog quantum computers to solve previously unsolvable problems Physicists observe rare resonance in molecules for the first time Qubits on strong stimulants Recreating the natural light-harvesting nanorings in photosynthetic bacteria Topological acoustic waveguide to help reduce unwanted energy consumption in electronics And others Seawater split to produce ‘green’ hydrogenSolid material that ‘upconverts’ visible light […]
Qubits on strong stimulants
Science Daily January 27, 2023 Optically active semiconductor quantum dots have unparalleled photonic properties, but also modest spin coherence limited by their resident nuclei. The nuclear inhomogeneity has thus far bound all dynamical decoupling measurements to a few microseconds. An international team of researchers (UK, Austria) eliminated the inhomogeneity using lattice-matched GaAs–AlGaAs quantum dot devices and demonstrated dynamical decoupling of the electron spin qubit beyond 0.113(3) ms. Leveraging the 99.30(5)% visibility of our optical π-pulse gates, we use up to Nπ = 81 decoupling pulses and find a coherence times hundreds of microseconds. This scaling manifests an ideal refocusing of strong interactions between the electron and the […]
MIT engineers grow “perfect” atom-thin materials on industrial silicon wafers
MIT News January 18, 2023 Two-dimensional materials and their heterostructures show a promising path for next-generation electronics. Nevertheless, 2D-based electronics have not been commercialized, owing mainly to three critical challenges: i) precise kinetic control of layer-by-layer 2D material growth, ii) maintaining a single domain during the growth, and iii) wafer-scale controllability of layer numbers and crystallinity. An international team of researchers (USA – MIT, UT Dallas, UC Riverside, Washington University, South Korea) has introduced a deterministic, confined-growth technique that can tackle these three issues simultaneously, thus obtaining wafer-scale single-domain 2D monolayer arrays and their heterostructures on arbitrary substrates. They geometrically confined the […]
Solid material that ‘upconverts’ visible light photons to UV light photons could change how we utilize sunlight
Phys.org January 30, 2023 Only about 4% of terrestrial sunlight falls within the UV range in the electromagnetic spectrum. This leaves a large portion of sunlight spectrum unexploited for photopolymerization to form a resin and activation of photocatalysts to drive reactions that generate green hydrogen or useful hydrocarbons (fuels, sugars, olefins, etc.). Photon upconversion (UC) could be the key to solving this problem. Researchers in Japan have developed a revolutionary solid film that can perform visible-to-UV photon UC for weak incident light while remaining photostable for an unprecedented amount of time in air. The film is completely solvent-free “green” formation […]
Solids that are also liquids: Elastic tensors of superionic material
Phys.org January 30, 2023 Superionics display both solid- and liquid-like characteristics: as solids, they respond elastically to shear stress; as liquids, they display fast-ion diffusion at normal conditions. They are technologically relevant for energy, electronics, and sensing applications. Characterizing and understanding their elastic properties are needed to address their feasibility as solid-state electrolytes in all-solid-state batteries. However, static approaches to elasticity assume well-defined reference positions around which atoms vibrate, in contrast with the quasi-liquid motion of the mobile ions in fast ionic conductors. Researchers in Switzerland have derived the elastic tensors of superionics from ensemble fluctuations in the isobaric-isothermal ensemble, exploiting extensive Car-Parrinello simulations. They applied this approach to […]
Recreating the natural light-harvesting nanorings in photosynthetic bacteria
Science Daily January 31, 2023 Photosynthesis in plants and some bacteria relies on light-harvesting (LH) supramolecules which come in different structures. So far, these LH molecules have not been artificially prepared. Researchers in Japan demonstrated that mixing a chlorophyll derivative with naphthalenediamide in an organic solvent leads to the formation of dimers that spontaneously self-assembled into ring-shaped structures, each several hundred nanometers in diameter. They observed that chlorophyll dimers, molecules composed of two chlorophyll units linked by naphthalene, initially self-assembled into stable wavy nanofibers. Upon heating these nanofibers at 50°C, they disassembled into smaller nanoring precursors whose ends eventually joined […]
An illuminated water droplet creates an ‘optical atom’
Phys.org January 31, 2023 When light scatters off a sphere, it produces a rich Mie spectrum full of overlapping resonances. Single resonances can be explained with a quantum analogy and result in Fano profiles. However, the full spectrum is so complex that recognizable patterns have not been found, and is only understood by comparing to numerical simulations. An international team of researchers (Sweden, Mexico) has shown the directional Mie spectrum of evaporating water droplets arranged in consecutive Fano Combs. They explained it by expanding the quantum analogy. This turns the droplet into an “optical atom” with angular momentum, tunneling, and […]
Lightning Strikes Create a Strange Form of Crystal Rarely Seen in Nature
Science Alert January 30, 2023 An international team of researchers (Italy, University of South Florida, Caltech, Princeton University) report the discovery of a dodecagonal quasicrystal Mn72.3Si15.6Cr9.7Al1.8Ni0.6—composed of a periodic stacking of atomic planes with quasiperiodic translational order and 12-fold symmetry along the two directions perpendicular to the planes. They found it in a fulgurite consisting predominantly of fused and melted sand along with traces of melted conductor metal from a nearby downed power line. According to the researcher fulgurite may have been created by a lightning strike that combined sand with material from downed power line or from electrical discharges from the downed power line alone. It reached temperatures of at least 1,710 °C as indicated by the […]
New analog quantum computers to solve previously unsolvable problems
Phys.org January 30, 2023 Tuning a material to the cusp between two distinct ground states can produce physical properties that are unlike those in either of the neighbouring phases. A tunable array of coupled qubits should have an appropriately rich phase diagram but realizing such a system with either tunnel-coupled semiconductor quantum dots or metal nanostructures has proven difficult. The challenge for scaling up to clusters or lattices is to ensure that each element behaves essentially identically and that the coupling between elements is uniform, while also maintaining tunability of the interactions. Advances in the fabrication and control of quantum […]
Study achieves the coherent manipulation of electron spins in silicon
Phys.org January 26, 2023 Electron spins in silicon quantum dots are excellent qubits because they have long coherence times and high gate fidelities, and compatible with advanced semiconductor manufacturing techniques. A team of researchers in the US (University of Rochester, industry) has shown that spin–valley coupling in Si, which drives transitions between states with different spin and valley quantum numbers, enables coherent control of single- and multi-electron spin states without oscillating electromagnetic fields. They demonstrated Rabi oscillations between effective single-spin states in a Si/SiGe double quantum dot that are driven by spin–valley coupling. Together with the exchange coupling between neighbouring electrons, […]